P1070: DECISIONAL ROLE OF INTERIM PET IN RELAPSED/REFRACTORY CLASSICAL HODGKIN LYMPHOMA TREATED WITH BEGEV CHEMOTHERAPY AS FIRST SALVAGE
Authors: Chiara Rusconi, Francesca Ricci, Rosa Daffini, Beatrice Casadei, Vittorio Ruggero Zilioli, Federico Mazzon, Vincenzo Marasco, Eleonora Calabretta, Chiara Pagani, Lisa Argnani, Cristina Muzi, Anna Guidetti, Marcello Rodari, Angela Passi, Sara Iadecola, Roberto Cairoli, Pier Luigi Zinzani, Alessandro Re, Paolo Corradini, Armando Santoro
Journal: HemaSphere (2023)

Topic: 17. Hodgkin lymphoma - Clinical Background: Achievement of complete response (CR) before autologous stem cell transplantation (ASCT) is one of the main predictive factors of outcome in patients (pts) affected by relapsed/refractory (R/R) classical Hodgkin Lymphoma (cHL). The predictive role of interim PET during salvage treatment is well established in pts treated with IGEV or ICE but has not been investigated in pts receiving BEGEV (Bendamustine, Gemcitabine and Vinorelbine) as first salvage treatment. Aims: With the aim to investigate the predictive value of PET after 2 cycles of BEGEV (PET2) in terms of CR rate and survival, we retrospectively collected data of consecutive R/R cHL pts eligible to ASCT treated from 2011 to 2022 in 5 Italian centres. Methods: PET scans were locally evaluated using Deauville Score (DS), considering a score 1-3 negative and consistent with CR. Early relapse was defined as a relapse occurring ≤12 months from the end of first-line therapy. Survival functions were calculated from the date of initiation of BEGEV. Results: One hundred sixty-eight cHL R/R pts receiving BEGEV as first salvage therapy were included. Eighty-nine (53%) pts were male. First-line therapy consisted in 2 to 6 ABVD cycles accordingly to stage followed by consolidation radiotherapy (RT) in 31 (18.5%) pts. At relapse, median age was 37 years (range: 16-71), 82 (48.8%) pts were in stage III-IV, 28 (16.7%) pts had B symptoms and 57 (33.9%) pts had extranodal involvement (EI). Ninty-three (55.4%) pts were primary refractory, 37 (22%) pts had an early and 38 pts (22.6%) a late relapse. PET2 was performed in 160 pts, and resulted negative in 102 (63.8%) and positive in 58 (36.2%) pts. PET after 4 BEGEV cycles (PET4) was performed in 153 pts and resulted negative in 115 (75.2%) and positive in 38 (24.8%) pts. Complete response after 4 BEGEV was achieved in 96/102 (94.1%) PET2 negative pts and 19/58 (32.8%) PET2 positive pts; PET2 positive pts had a lower probability to achieve CR at PET4 when compared to PET2 negative pts (Odds ratio: 0.04, CI 95%: 0.01-0.11; p<0.001). Autologous SCT was performed in 148 (88.1%) pts, following BEGEV in 101/148 (68.2%) and after further salvage treatments in 47/148 (31.8%) pts. Consolidation post-ASCT was performed in 38 (22.6%) pts, and consisted in RT in 26 pts and brentuximab-vedotin in 12 pts; 14 pts received an allotransplant, in 9 cases performed after further post-ASCT salvage treatments. With a median follow-up of 33.4 months (IQ range: 19.8-49.4), 2-years overall survival (OS) and progression-free survival (PFS) for the whole study population were 93.8% (CI 95%: 90.1-97.6) and 62.2% (CI 95%: 55-70.2). No significant differences in OS were detected according to PET2 result, while 2-years PFS was significantly superior in PET2 negative vs PET2 positive pts: 2-years PFS was 77.6% (CI 95%: 69.6-86.6) in PET2 negative and 40.9% (CI 95%: 29.9-55.9) in PET2 positive pts (p < 0.0001) (Figure 1). Multivariate Cox regression model of PFS evaluating PET2 result and presence of adverse clinical characteristics at relapse such as EI (HR 1.00, CI 95%: 0.58-1.71), time to relapse (primary refractory and early relapse vs late relapse, HR 0.66, CI 95%: 0.36-1.20) and presence of B symptoms (HR 0.64, CI 95%: 0.30-1.36), identified PET2 positivity as the only predictive factor for PFS (HR 4.43, CI 95%: 2.59-7.57, p<0.001).Summary/Conclusion: In conclusion, R/R cHL pts with PET2 positive during BEGEV salvage treatment had a lower probability to achieve CR after 2 additional BEGEV cycles and a significantly inferior PFS, and could benefit from early exposure to new therapeutic strategies before ASCT. Figure 1: PFS according to PET2 resultsKeywords: Hodgkin’s lymphoma, Salvage chemotherapy, relapsed/refractory, Autologous hematopoietic stem cell transplantation